The transcriptional regulation of simian virus 40 genes in the cells transformed by SV 40 is being investigated at the chromatin level. The possible role that chromosomal proteins play in the partial expression of SV 40 genome from chromatin is being investigated by the method of chromatin reconstitution. Also, the binding specificity of viral internal proteins to DNA in SV 40 and the transcriptional pattern from SV 40 nucleoprotein are being compared with the chromatin isolated from transformed cells with the use of restriction endonucleases and RNA-DNA hybridization method. BIBLIOGRAPHIC REFERENCES: Chae, C-B., Gadski, R.A., Carter, D.B., and Efird, H., "Integrity of Proteins in Reconstituted Chromatin", Biochemical Biophysical Research Communications, 67, 1459-1465, 1975.